1. Field of the Invention
This invention relates to a method and apparatus for maintaining a glue applicator in condition for applying cold glue, which glue applicator includes a multiplicity of nozzle orifices, and more particularly to a method and apparatus for maintaining a glue nozzle in ready-to-flow condition and operable after both short and long stoppages of conveying apparatus that conveys the articles to which the glue is applied.
2. Description of the Prior Art
It is known to apply liquid glue to an area of predetermined size by means of glue-applying rollers or glue-applying nozzles. Glue-applying nozzles permit the glue to be applied in a more economical manner because they apply the glue in narrow stripes rather than over an entire surface. It is also known that glue can be applied to predetermined areas of webs or workpieces that are moved continuously past a stationary glue applicator that is provided with glue-applying nozzles, each of which nozzles is provided with a valve, preferably with a solenoid valve, to permit precise timing of the initiation and duration of the discharge of glue. However, when liquid glue is applied by means of nozzles, a serious problem can arise when the movement of workpieces is stopped because the nozzle orifices of the glue-applying nozzles can be clogged by glue that has set or solidified during the stoppage, so that resumption of glue flow is impeded when workpiece movement is resumed.
It is an object of the present invention to permit an application of glue by means of glue-applying nozzles in such a manner that clogging of the glue-applying nozzles with solidified glue does not arise during workpiece movement stoppages, so that that glue flow can be resumed immediately upon resumption of workpiece movement.